fS:34OO(PartXVII)-1974 ' Indian Standard METHODS OF TEST FOR VULCANIZED RUBBERS PART XVII TEAR STRiNGTH-ANGULAR ( Second Reprint MAY 1988) ( Reaffirmed 2003 ) TEST PIECE UDC 678.43:620.176.245 BUREAU MANAK OF INDIAN STANDARDS BHAVAN, 9 BAHADUR SHAH ZAFAR MARG NEW DELHI 110002 Gr2 December 1974 IS : 3400( Part XVII ) - 1974 Indian Standard METHODS OF TEST FOR VULCANIZED RUBBERS PART XVII TEAR STRENGTH Products Sectional L TEST PIECE -ANGULAR Committee, Rubber chailman DR D. BANERJ~G CDC 6 RcpreSCNf itq &con Consultants Pvt Ltd, Calcutta MambCTZ SHRI A. T. BASAK SHRl s. K. Bose SHRI A. GHOSH (Alfmnte ) Alkali Sr Chemical Corporation of India Ltd, Calcutta SHRI D. K. CIIATTERJEE DR S. K. RAY ( Alfmatc ) Export Inspection Council of India, Calcutta SHRIS. S. CHOPRA SHRI K. M. BIJI.I ( Alfernafe ) Ministry of Defcnce ( R & D ) SHRI S. L. GANDHI SHRI M. G. BHAR~AVA ( A~fcrt~fc ) Hindustan Steel Ltd, Ranchi SWRI G. <:. jA1N Railway Board SHRI 0. i%.KOIILI Ministry of Dcfence ( DC1 j SHR~ M. KUU.\RAN Cosmos India Rubber Works Pvt Ltd, Bombay SHRI LALIT MOH.AY .JAMNADAS SHR~ PuI.I:; 1.. hwARlWALA ( ~&ernate ) Lathia Rubber Manufacturing Co Pvt Ltd, Bombay SHRI s. v. L,%I.i!l:\ SHRI D. P. L.?x 1::~ ( Alfcrnnfe ) Madras Rubber Factory Ltd, Madras Smr S. K. MATTHAN SHRT K. J. ABRAHAM (Alfenzafe) All India Rubber Industries Association, Bombay DR K. N. MODAK SHRI K. R. SENGUPTA ( Alfernofe ) Dunlop India Ltd, Calcutta SHRI S. MUKHERJEE SHRI P. N. S. MYER ( Alfemfc ) Rubber Board, Kottayam DR C. K. N. NAIR Bata India Ltd, Calcutta SHRI S. C. NANDY Bayer ( India ) Ltd, Bombay SHR~ R. R. PANDTT Synthetics & Chemicals Ltd, Bombay .%fRl ht. M. PA-I-EL Indian Oil Gorporation Ltd, Bombay SHRI K. RAJQOPAUL Directorate General of Technical Development, New DR N. V. C. RAO Delhi SHRI G. R. INAMDAR ( Alternate ) Directorate Gcncral of Supplies Delhi National Test House, Calcutta & Disposals, New @ Copyrichf 1974 BUREAU OF INDIAN STANDARDS This publication is protected under the I&an Copyright Acr (XIV of I.957 ) and reproduction in whole or in part by any means except with written permission of the publisher shall be deemed to be an infringemenr of copyright under the said Act. SHar AmTAmih thR~ R. c. SYBD lumbers Sxmr B. ROY itl?pfesenfing SEN ( Aknlab ) National Rubber Manufacturcn Ltd, Calcutta Research Association, Industries As&a- SHru s. K. GHosH ( Altu?&Yh) SHRI D. D. TALWALKAR Indian Rubber Manufacturers' Bombay All India Automobile tion, Bombay & Ancillary Swnr K. M. KHALADKAR (Akin&) &XXI D. D.u GUPTA, Director General, BIS ( &e&k Deputy Director General *clorv SHRI SATQH CHANIJ~R Deputy Director ( Cbem ), BlS Mkabfl ) Methods of Testing Vulcanized Rubbers Subcommittee, C-r M. M. PATJJL M#l?lbtTS SHRI CDC 6 : 9 SHRl Synt&ia Et Chemicals Ltd, Bombay Shrl M. M. Pate1 ) National Test House, Calcutta Ssm1 S. K. Boss SHRI A. GHOSH ( Ahmate ) Bayer ( India ) Ltd, Bombay DR S. N. CAUCRAVARN DR S. K. BH~TNAGAR(Al&ma& ) Alkali & Chemical Corporation of India Ltd, Calcutta SHRI D. K. CI~ATI-YIRJEE SHRI K. R. SESHADRI (AI&mate ) Cknmos India Rubber Works Pvt Ltd, Bombay Ssxm B. H. DALAL SHR~PIJLZN L. K~NARIWALA ( Akmak ) Dunlop India Ltd, Calcutta SHRI S. B. GANGULY SHRI A. MIJ%H~x@~ ( Al(rmok ) Madras Rubber Factory Ltd, Madras SHRI A. GEORGEJOHN SHRI G. R. SANRARANARAYANAN( AIfcmafe) Ministry of Defence ( DGI ) Smt~ R. K. GWFA Indian Rubber Regenerating Co Ltd, Bombay SHRI G. R. KA~SHWAR SHRI A. R. -AK ( Ahtab ) Railway Board DR S. P. MANIK SHRI G. DORAISWAYY( Alemarc ) Rubber Board, Kottayam DR C. K. N. NAIR Swastik Rubber Products Ltd, Poona SHRI V. D. PANDSE SHRI S. V. TA~I~AWADKAR( Alternate ) Sundaram Industries Pvt Ltd, Madural SHRI V. R. RAO SHRI K. c. ~HMUDI&WIAN (Akm& ) National Rubber Manutketurers Ltd, Calcutta SHRI B. ROY SHRIJ. CHA~TERJEE ( Alkmafu ) Bata India Ltd, Calcutta !&RI S. SARKAR SHRX S. ROY ( Alkmak ) Escon Consultants Pvt Ltd, Calcutta SHRI A. K. SBN CHAUDHURI Hindustan Latex Ltd, Trivandrum DR N. H. SIVARAXAKRI~HNAN Premier Rubber & Cable Industries, Bombay SHRI M. SALIMVOHRA Swru A. D'XXJ~TA ( Altsmatr ) N. M. RXGE ( Alfmrat~ to 2 ISt34oo(PartXvIl)-1974 Indian Standard METHODS OF TEST FOR VULCANIZED RUBBERS PART XVII TEAR STRENGTH-ANGULAR TEST PIECE 0. FOREWORD 0.1 This Indian Standard ( Part XVII ) was adopted by the Indian Standards Institution on 10 March 1974, after the draft finalized by the Rubber Products Sectional Committee had been approved by the Chemical Division Council. 0.2 The tear strength depends on the dimension of the test piece, speed of stretching, temperature of test and the stress distribution in the test piece; hence the test is satisfactory only for laboratory comparison and not as a service test. The tear strength is particularly susceptible to grain effects in vulcanized rubber. 0.3 Method of test for tear strength employing crescent already been published as Part XII of this standard. test piece has 0.4 This standard is mainly based on ASTM Designation D 624-54 ( Reapproved 1970 ) ( Standard method of test for tear resistance of vulcanized rubber ' issued by the American Society for Testing and Materials. 0.5 In reporting the result of a test or analysis made in accordance with this standard, if the fmal value, observed or calculated, is to be rounded off, it shall be done in accordance with IS : 2-1960*. 1. SCOPE 1.1 This sta+rd ( Part XVII ) prescriber the method for determination of tear resistance of the usual grades of soft vulcanized rubber employing an angular test piece. This method is not suitable for the testing of the material ordinarily classed as hard rubber. 2. APPARATUS 21 Tensile Testing Machine - The machine shall be power driven and ofsuch capacity that the maximum load required to break the test specimen l Rulci for rounding 0E numericalvalues( r&.ruff ). 3 IS : 3400 ( Part XVII ) - 1974 shall not exceed 85 nor be less than 15 percent of the rated capacity. The rate of travel of the grip shall be 50 f 2 cm/mm and shall be uniform at all times. The machine shall be equipped with a type of grip which tightens automatically and exerts a uniform pressure across the gripping surfaces increasingly as the tension increases, so as to prevent uneven slipping? and to favour failure of the specimen in its constricted section. It is advisable to have at the end of each grip a positioning device so that all specimens are inserted to the same depth in the jaws and are perpendicular to the direction of pull. NOTE - Inertia ( pendulum ) type dynamometers arc apt to give results which dither because of frictional and inertial effects. An inertia-less ( for examplr, electronic or optical transducer type ) dynamometer gives results which are free from these effects, and is therefore to be preferred. 2.1.1 Calibration of Temile Testing Machine -The load scale and the recording mechanism shall bc calibrated at least once a week to ensure that the load scale error does not exceed 2 percent of the applied load. 2.2 Die for Test Specimens -- The specimens for tear resistance test shall be stamped out with the steel die conforming to the dimensions shown in Fig. 1, the cutting edges of which shall be kept sharp and free of all nicks to avoid leaving ragged edges on the specimens. It is important that the apex of the 90-degree angle *be sharpened to provide a sharp comer. Good cutting edges are best obtained by careful honing. The rubber may be wetted with water or soap solution and shall be supported on a sheet of slightly yielding material ( namely, leather or cardboard) on a flat rigid surface. Normally all test pieces shall be prepared with grain at ri&t angles to their length. +--=-100 MIN 9o" 19 R I I 19 4 k2.5 R * 25R 27 5QF J -204 7 Tolerance * 0'05 All dimensions in millimetres. FIG. 1 DIES FOR TEAR TEST SPECIMENS 4 IS t 3400 ( Part XVII ) - 1974 3. TFST SPECIMEN 3.1 The test specimen shall conform to the shape shown in Fig. 1. The thickness of the specimen shall be measured, with the micrometer graduated to @I mm exerting a total force of 200 g/cm* on the rubber. Four measurements of thickness in the region of the test area shall be made including one at the apex of go-degree angle and the average value should be used. The thickness of the test piece shall not fall outside limits of 1.8 to 2.8 mm. The thickness in the region of the test area shall nowhere deviate by more than 2 percent from the mean. is well known fact that vulcaniaed rubber exhibits a grain effect which NoTe -It influences its physical properties. In the case of heavily loaded compounds, the effect may produce a pronounced difference in physical properties. The grain direction shah be clearly marked on materials to be tested. Usual practice is to test with the grain Data so obtained shah be recorded as tear running along the length of the specimen. resistance ( pulling ) with the grain and it is assumed that unless otherwise specified, ail test specimens are to be prepared in this manner. Where grain effects are significant and are to be evaluated, an additional set of test specimens shall be cut with grain running across the specimen. Data so obtained shall be recorded as tear resistance ( pulling ) across the grain. 3.2 Number of Test Specimens -Three specimens per sample shall be tested for tear resistance. The value reported shall be the average of those observed. If any value deviates more than 20 percent from this average, two additional specimens shall be tested and the median of all five values shall be reported. 4. TEMPERATURE OF TEST 4.1 Carry out the test at 27 f 2°C unless otherwise specified. Some synthetic rubbers have markedly lower tear strength at elevated temperatures and hence tests may also have to be carried out at higher temperature, 100°C being the useful temperature. 5. PROCEDURE 5.1 Preparation of Sample from Finished Rubber Goods - IC is attached or embodied in rubber sample, remove the same before cutting the test piece. Prefierably avoid the use of a swelling agent while removing the fabric, but benzene, chloroform or carbon tetrachloride may be used to wet the contacting surface, if necessary. Take care to avoid stretching of the rubber during the separation from the fabric, and if swelling liquid is used, allow the same to evaporate completely from the rubber surfaces after separation. Make the cloth marked surfaces smooth by buffing. Buff as and when necessary the rubber sample which is of uneven thickness or of thickness above the maximum specified for the test piece which is to be cut from it. If agreed to between the purchaser and the supplier, test pieces of thicknesses other than what have been prescribed fabric 5 IS : 3400 ( Part XVII ) - 1974 However, in such cases it shall be within the range in3.1 may be used. 1)uring buffmg avoid undue heating of the rubber. of 0.8 to 3 mm. 5.2 Conditioning of the Moulded Test Slab - The properties of vulcanized rubber change continuously with time, these changes being particularly rapid during the first 24 hours after vulcanization. JIo not carry out any test within this period; for accurate comparisons .bctucen diff'crent rubbers it may be necessary to ensure that these are tested at substantially the same interval after \rulcanization. Protect test slabs and test pieces as far as possible from light. Condition samples after any necessary prcparation at 27 4; 2°C for not less than 3 hours immediately before testing. When cart-yin? out tests at clevatcd temperature, the test piece shall be kept at that tcmpcraturc for 15 minutes. 5.5 Determination of Tear Resistance - Clamp the specimen for test in the jaxvs of the testing machine, taking care that the ` bite ' of the jaws shall be at the rentre of the tab ends and in line with the direction of load application. Apply the load with a Jowcr jaw speed of 50 cm per minute. After rupture of the sprcimcn, note the breaking load from the dial or scale and record together with the average thickness of the spccimcn. 5.4 Calculation -- Tear strength is calculated by dividing the load in kg bv the tIli&ncss in centimetrc of the test specimen and expressed as kg/cm thickness. 5.5 Report ---'1'11~ rtport a) the calculated 1~) direction c) temperature sbaJJ state: to grain; and tear strength; of test, if other than 27 f 2°C. in which test piece is cut relative BUKEAU OF INDIAN STANDARDS Shah Zafar Marg, NEW DELHI 110002 Telegrams : Manaksanstha ( Common to all Offices ) Telephone Headquarters : Manak Bhavan, 9 Bahadur Telephones: 3 31 01 31,3 31 13 75 Regional Offices : `Western E9 MIDC, Maroi, Andheri ( East ). 6 32 92 95 BOMBAY 400093 tEastern : l/14 C. I. T. Scheme VII M, V. I. P. Road, 36 24 99 Maniktola, CALCUTTA 700054 Northern . SC0 445-446, Sector 35-C 2 18 43 CHANDIGARH 160036 { 31641 Southern : C. I. T. 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